The four remaining "classic" color tools (Brightness-Contrast, Curves,
Levels and Threshold) are in fact just special UIs for otherwise
completely normal filter ops.

Add normal filter actions for them and invoke them like all
other filters, which makes them show up in the filter history
automatically.

The only small hack needed is to special case them in
gimp_gegl_procedure_execute_async() so the right tools are created
instead of the default GimpOperationTool. Also, blacklist the
automatically generated tools actions from action search and the
shortcut editor.